Mold



Jan. 18, 1949. H- ZAHN 2,459,402

HOLD

Filed Feb. 26, 1944 Patented Jan. 18, 1949 UNITED STATES PATENT OFFICEMOLD Eric H. Zahn,

Pound Rid Austenal Laboratories, N. Y., a corporation of ge, N. Y.,aasignor to Incorporated, New York, New York Application February 2.6,1944, Serial No. 524,025 3 Claims. (Cl. 22-154) This invention relates,generally, to molds, and 'has particular relation to improvements inhollow casting molds having one or more casting cavities theconfiguration and volumetric proportions of which are the same as apredetermined pattern.

In the production, for example, of wax or like patterns for use is castand avoidance of distortion of the pattern are of primary importance. Asan illustration, in the production of turbine buckets such as disclosedin the copending application of Albert W. Merrick, Serial No. 422,421,led December 10, 1941, now Patent 2,381,459 issued Aug. 7,

ance with the above patent have proved to be highly emcient in castingpatterns of wax or proportions ofv the patterns cast therein. Thisrenders the patterns inaccurate and causes corresponding objectionableinaccuracy in the final casting produced in molds formed about thepattern.

pressure to which the mold sections are subjected during the operationof casting the pattern in the mold.

each of the mold sections a forming element of relamounted in hardpressure More specifically, preferably comprises tively soft materialmeans operating through the forming element of that of casting thepattern, whereby the relatively soft forming elements of the moldlsections are not subjected to such pressure and slow flow of the metalof the forming elements, with resultant inaccuracy of the mold cavity,is avoided. Further objects and advantages of my invention will appearfrom the detail description.

In the drawings:

Figure 1 is a plan view of the lower section of a mold embodying myinvention;

Figure 2 is a section taken substantially on line 2-2 of Figure 1,through the upper and lower sections of a mold embodying my inventionand through the knockout pins guard plate;

Figure 3 is a sectional view taken substantially on line 3-3 of Figure2; and

Figure 4 is a fragmentary sectional view taken substantially on line 4-4of Figure 1.

I have shown my inventiony by way of illustration, as embodied in a moldfor producing patterns for articles of generally rectangular shape inplan and of concavo-convex cross section. This'mold comprises an uppersection 5 and a lower section 6. In forming section 6 of the mold Ifirst provide a reinforcing member 1 of rectangular shape in plan andsuitable thickness, conveniently formed of cast iron, or other suitablereinforcing material, having in its upper face a rectangular recess ofuniform depth and of appropriate length and width suitable to theforming element of the mold to be received therein. The reinforcingmember 1 is suitably finished by machining or otherwise, and has formedtherein suitably disposed registering sockets 8. After the member 1 hasbeen machined and finished and the registering sockets 8 have beenapplied thereto, a forming element 9 is cast in the recess in member 1,about a suitable pattern, in accordance with the method of my aboveidentified prior patent. This element 9 is cast of a suitable alloy,such as the tinbismuth alloy as referred to in said patent, which isrelatively soft and has a low melting point, or of any other suitablematerial.

It is assumed, for purposes of illustration, that the pattern selectedis such as to provide, in the exposed upper face of element 9, which maybe referred to as its forming face, a plurality of recesses I ofrectangular shape in plan and of arcuate cross section, these recesses-belng connected by pouring passages II of semi-circular cross sectionextending lengthwise of forming element 9, and relatively short passagesIla, also of substantially semi-circular cross section, extendingtransversely of forming element 9 and opening from passages Il into theends of the depressions I0. Incastng the forming element 9 in thereinforcing member 1, the latter member is in inverted position, 4beingprovided through its then upper wall, which is its bottom wall in thenormalposition of member 1, cating sprue and gate openings. The gateopening may are outward of member 1. The reinforcing member 1 is heatedto a suitable temperature and the molten alloy is poured or injectedinto member 1 about the pattern, over which is disposed the rubbermembrane, in the manner described in my above referred to patent. Afterthe alloy has cooled and-set to a proper extent, the member 1, with theforming element 9cast and retained in the recess thereof, is rcmovedfrom the pattern. The sprue and gate openings of the member 1 are lledwith the alloy of member 9, providing sprue and gate elements I2 and I3extending through the bot- '4 tom wall Il of member 1,-as shown. .Itwill bc noted that the areas of forming element 9 extending outwardbeyond the passages and depressions in the upper face thereof are ushwith the upper face of the surrounding wall of the reinforcing member 1,for a purpose which will appear presently. The forming element 9 isfurther provided, at the -idcs of passages II and Ila, with narrowhorizontal shoulders I and with beveled surfaces I6 extending upward andoutward from the shoulders I5, to give the proper parting line for thesepassages, as will appear more fully later.

After the lower mold section 6 has been pro-Y duced in the manner abovedescribed, the pattern is placed in this lower mold section, and theupper mold section is then produced, this upper section comprising anouter reinforcing member I1, conveniently formed of cast iron or othersuitable reinforcing material; The reinforcing member I1 is machined andfinished, and is provided with registering dowel pins I9, these pins andthe sockets 8 being accurately located with respect to each other toassure accurate register of the two mold sections, in a known manner.The reinforcing member I1 is placed upon the lower mold section 6 inaccurate register therewith, and over the pattern and the rubberdiaphragm disposedvthereover mounted in the lower mold section, afterwhich the molten alloy is poured or injected into the recess inreinforcing member l1. The forming element I8 is thus cast and retainedin reinforcing element I1 and is provided with sprue and gate elementsand 2 I as shown.

After the lower mold section has been produced in the manner described,it is bored out from its lower face to provide a plurality of suitablydisposed rbores 23, from the upper end of each of which extends aconcentric bore 24, of reduced diameter, opening into a coaxial boreextending through forming member 9 'at the mid-width of one of thepassages II or Ila therein. The upper portion of bore 25 is counterboredto provide a downwardly tapering irusto-conical seat 25a in which s eatsthe correspondingly shaped head 26 of a knock-out pin 21 slidabiymounted through bore 24. Pin 21 extends downward beyond the bottom faceof wall I4 of reinforcing member 1 and is urged downward, by acompression spring 28 disposed about pin 21 within bore 23 and confinedbetween the wall at the upper end oi this bore and a washer 29 mountedon pin 21 and restrained against downward movement therealong by the pin3l] pin 21. Spring 28 normally holds head 26 of pin 21 seated againstthe seat 25a so as to form a huid-tight closure therewith. In the use ofthe mold, the projecting ends ofthe pins 21 extend into recesses. 3| ina removable steel guard plate 33 disposed at the bottom or back wall I4of mold section 5.

vReferring to Figures 2 and ment I8 of the upper mold section isprovided with rounded projections 34 overlying the depressions I0 in theforming element 9 and deflning therewith mold cavities of concave-convexcross section. the upper edges of which are in thev plane of the upperface of the peripheral wall of 3, the forming elereinforcing member 1 ofthe lower mold section.

The upper mold section forming element I8 is further provided withlengthwise passages 35 and with relatively short transverse passages 36cornplementary to passages Il and IIa, respectively, of forming element9, and has downwardly exsecured through l lower portion of plate 4U tsThe sprue and in any suitable being provided with a notch'--42 ,in whichthe snugly. and reinplate I0, and a sprue opening 43 concentric withsocket I2 and extending through the two mold sections and opening intopassage il at the top thereof.

The wax is injected into the mold cavity by means of an injector or gunhaving a nozzle which seats tightly the guard plate 33, the knock-outpins 21 are moved simultaneously upward through the lower known manner,having a mold cavity conforming accurately to the wax pattern. Thisrefractory in the gate or socket 2 mold is then used for casting thereinthe desired article.

It will be noted that the mold shown and described herein ing to thepassages defined by the semi-circular passages or depressions Il, Ila,and v35 and 36 entirety of the alloy, thus eiectlng a material saving inthe alloy or other material used for the forming elements of the moldsections.

cavity in said lining from outside said outer members with the moldsections assembled in casting relation, ejector means slidingly mountedin and guided by at least one of said outer members and operable throughits softer lining into engagement with the object cast in said cavity toeject same from the casting cavity, said ejector means being normallyconstrained to a position projecting from the outer surface of theadjacent outer reinforcing member, and a removable guard plate fittingagainst the outer surface of said outer member in position covering saidejector means and having a recess for receiving said ejector means toguard said ejector means against actuation and permit application of theguard plate to said outer member Without actuating said ejector means.

2. In a casting mold of the class described, in combination, a pluralityof complementary mold sections each consisting of an outer hard and wearresistant reinforcing shell member and an inner lining of low [usingcast metal softer than said outer reinforcing member and fitting tightlywithin said outer wear resistant shell member, the face of at least oneof said relatively soft linings which is opposed to the cooperating faceof the other lining having a casting cavity of a shaft for casting thedesired object, said linings completely enclosing and defining. thecasting cavity throughout its entire extent so that none of the surfacesof said outer members is exposed to said cavity, registering ingateopenings one in said lining and the other in at leastone of said outermembers through which the molten material to be cast is introduced intothe casting cavity in said lining from outside said outer members withthe mold sections assembled in casting relation, ejector means slidinglymounted in and guided by at least one of said outer members and operablethrough its softer lining into engagement with the object cast in saidcavity to eject same from the casting cavity, said ejector means beingnormally constrained to position projecting from the outer surface ofthe adjacent outer reinforcing member, and a removable guard platefitting against the outer surface of said outer member in positioncovering said ejector means and having a recess for receiving saidejector means to guard said ejector means against actuation and permitapplication of the guard plate to said outer member without actuatingsaid ejector means, said guard plate being disposed at the bottom of themold to support the same and said ejector means being adapted to beactuated to ejecting position by placing the cooperating surface of theouter member of the mold upon a support with said guard plate removed.

3. In a casting mold of combination, a plurality of complementary moldsections each consisting of an outer hard and wear resistant reinforcingshell member and an inner lining of low fusing cast metal softer thansaid outer reinforcing member and fitting tightly within said outer wearresistant shell member, the face of at least one of said relatively softlinings which is opposed to the cooperating face of the other lininghaving a casting cavity of a shape for casting the desired object, saidlinings completely enclosing and defining the casting cavity throughoutits entire extent so that none of the surfaces of said outer members isexposed to said cavity, registering ingate openings one in said liningand the other in at least one of said outer members through which themolten material to be cast is introduced into the casting cavity in saidlining from outside said outer mem- ,bers with the mold sectionsassembled in casting relation, ejector means slidingly mounted in andguided by at least one of said outer members and operable through itssofter lining into engagement with the object cast in said cavity toeject same from the casting cavity, said ejector means being normallyconstrained to position projecting from the outer surface of theadjacent outer reinforcing member, a removable guard plate fittingagainst the outer surface of said outer member in position covering saidejector means and having a recess for receiving said ejector means toguard said ejector means against actuation and permit application of theguard plate to said outer member without actuating ysaid ejector means,and spring means confined entirely within the adjacent outerreinforcing' member of the mold and coacting'with said ejector meansnormally to constrain said ejector means to nonejecting position.

ERIC H. ZAHN.

REFERENCES CITED The following references are of 'record in the file ofthis patent: I

UNITED STATES PATENTS the class described, in

